OS6A-1:A THERMODYNAMIC STUDY ON THE EFFECTS OF SO2 ON CO2 SEPARATION FROM FLUE GASES BASED ON GAS HYDRATE CRYSTALLIZATION PROCESS

Zhao-Yang CHEN1, Chao CHEN1,2, Xiao-Sen LI1,*, Zhi-Ming XIA1, Qiu-Nan LV1, Chun-Gang XU1
1. Guangzhou Centre for Gas Hydrate Research, Guangzhou Institute of Energy Conversion, CAS, CHINA; 2. University of Chinese Academy of Sciences, CHINA.

    Separating CO2 from the coal-fired flue gas based on gas hydrate crystallization process is considered as a novel, green and low energy consumption method. However, almost all investigations on this technology simplified the feed flue gas as CO2 and N2 mixtures. The component of SO2 is not considered in the hydrate separation process. In practical industrial separation process, the chemical additives containing aqueous solution must be recycled. Due to the high solubility of SO2 in water, the residual SO2 in desulfurized flue gas would accumulate to a high concentration in the solution after multiple cycles unless an expensive stripping-off process is adopted. In this work, the effect of SO2 on the hydrate formation conditions of SO2 containing simulated flue gas is studied by a self-developed experimental apparatus, and the cage occupation of gas composition in the SO2 containing hydrates is studied by Raman spectroscopic analysis. The results indicate that the presence of SO2 is beneficial to the hydrate formation when the SO2 concentration is less than 1.0 wt% in TBAB containing solution system, while the high concentrated SO2 inhibits the hydrate formation. SO2 competes with CO2 in occupying the small cages of TBAB semiclathrate hydrates. The high SO2 concentration in aqueous solution deteriorated the separation and capture effect of CO2.